SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '944ebee26ec5b716b0594d88b494a3da40f7d0d16b36ed489b297913fc7d5aaf' 
  AND token = 'pDBwWcbErP4WBMFyKpxw+jBQwpBIaHFMbvXqUqZOjP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}